Answer:
The boiling point is the temperature at which a liquid boils and changes into a gas. At the boiling point, the vapor pressure of the liquid is equal to the atmospheric pressure.
The melting point is the temperature at which a solid changes into a liquid. At the melting point, the solid and liquid phases are in equilibrium and the substance can exist in either phase.
The boiling point and melting point of a substance depend on the intermolecular forces between the molecules in the substance. Substances with strong intermolecular forces, such as covalent compounds, tend to have higher boiling points and melting points than substances with weaker intermolecular forces, such as ionic compounds. The boiling point and melting point of a substance also depend on the pressure under which the substance is being heated or cooled. For example, the boiling point of water is lower at high altitudes, where the atmospheric pressure is lower.